Obstruction of the left subclavian artery is one of the rarest causes of the cogenital subclavian steal syndrome with a right-sided aorta. Radiological diagnosis can be made from a standard film which shows the aorta on the right, and a barium examination of the esophagus which demonstrates the absence of any compression posteriorly. Angiographic exploration (aortography, pulmonary angiography) is essential for positive confirmation of diagnosis and to exclude other types of congenital subclavian steal with a right-sided aorta. Certain cardiac malformations may be associated, but forms have been described without any other anomalies as in the case reported, which only became apparent when neurological symptoms developed in adult age.